Universal joint construction

ABSTRACT

A permanently lubricated and sealed universal joint utilizing an annular element constituting both a thrust washer and a seal for retaining grease, the element having a flexible sealing flange around its outside diameter, a rigid centering flange depending from the internal diameter, and thrust bearing surfaces, one of which has equally angularly spaced grease-retaining pockets.

United States Patent [451 Mar. 21, 1972 Sheppard, Jr.

[54] UNIVERSAL JOINT CONSTRUCTION [7 2] Inventor: Cecil James Sheppard,Jr., Gobles, Mich.

[73] Assignee: Compact Tractor Industries, Inc., Allegan,

Mich.

[22] Filed: Apr. 1, 1970 [2]] Appl. No.: 24,704

[52] U.S. Cl "64/17 SP, 277/212 [51] Int. Cl. ..Fl6d 3/26 [58] Field ofSearch ..64/ l 7; 277/212 [56] References Cited UNITED STATES PATENTS3,457,732 7/1969 Decouzon.....

3,481,159 12/1969 Kayser ..64/17 A Primary Examiner-Edward G. FavorsAttorney-Price, Heneveld, Huizenga & Cooper ABSTRACT Jarvis et a1. "bt/l7 PATENTEDHARZI 1972 3,650,123

SHEET 1 OF 2 UNIVERSAL JOINT CONSTRUCTION BACKGROUND OF THE INVENTIONMany conventional universal joints utilize yokes and centerblocks, theyokes and center-block being jointed together by a pin or bearing sothat the yokes are in contact with the centerblock or pin, requiringgrease to be interposed between such members. The difficulty with suchan arrangement is that the grease is free to eventually work its way outfrom between the contacting surfaces, resulting in a gradual increase infriction and attendant wear between the two contacting surfaces. Thisnecessitates periodic regreasing of the joint, and, of course, is theprimary reason for early failure and malfunction. To allow such jointsto be repaired, devices such as clip retainers must be utilized. Suchdevices inevitably result in an increase in swing diameter, a veryundesirable characteristic in compact power trains or steering linkages.

SUMMARY or THE INVENTION This invention relates to a new form ofuniversal joint construction, and to a novel thrust washer seal utilizedin combination with a universal joint and/or a hearing, whichcombination avoids the aforesaid disadvantages of conventional joints byproviding a permanently greased joint. Briefly stated, the inventionprovides a thrust washer seal comprising a flexible annulus, the annulushaving two thrust bearing surfaces and means for sealing grease toprevent leakage away from at least one of such surfaces. The thrustwasher can be utilized in combination with a bearing forcibly engagedwithin the annu- Ins and with a center-block and yoke which comprise auniversal joint.

Accordingly, it is a major object of the invention to provide a compactuniversal joint having a minimum swing diameter.

It is a related object of the invention to provide a joint of the abovecharacter which is permanently greased and sealed so as not to requirefittings or disassembly for regreasing.

It is another object of the invention to provide a joint of the abovecharacter having a novel combined thrust washer and grease seal whichpermanently maintains grease within the bearing so as to preventbreakdown.

It is still another object of the invention to provide a joint of theabove character wherein the thrust washer seal is permanently positionedbetween the metal parts, so as to absorb thrust generated by thoseparts.

The foregoing objects and advantages of the invention, as well as othersequally a part thereof, will become apparent upon reference to theattached drawings and the following more detailed discussion.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENTS The invention relates to a permanently greased, sealed jointwhich can be utilized in a universal joint construction such as thatillustrated at in FIG. 1. Such a joint is basically of the block and pintype, which is greased only initially. More particularly, the jointutilizes a pair of yokes 12 having flat parallel internal sides, whichare pinned to a cubical center-block 14 (FIGS. 1 and 4) by trunnion pins18 which are press-fitted into holes 19 in the block. The universaljoint so illustrated also uses a needle-bearing assembly 20 rotatablyaccommodating one end of each trunnion pin 18 (FIG. 4). Basically, thesebearing assemblies comprise a thin-walled cuplike shell whosecylindrical wall is lined with a series of needle-bearing elements, andsuch an assembly is now widely available commercially.

In accordance with the invention, the entire joint is permanentlygreased and permanently assembled, thereby providing for greatlyimproved performance, as well as significantly reducing the allowablesize of the joint and its swing radius. That is, the trunnion pins 18are press-fitted into the center-block 14, and the outer shell of theneedle bearing assemblies 20 is press-fitted into each of the differentopenings 22 in the yokes l2. 7

As important part of the invention is a thrust washer seal 30, which ispositioned between the center-block l4 and the adjacent arm of the yoke12 to absorb the thrust developed between the two metal parts. This sealis also press-fitted over the outer shell of the bearing 20, to completethe permanently assembled, sealed configuration of the joint. The pressfit of the seal 30 over the bearing 20 is readily accomplished, due tothe outer diameter of the bearing shell being only slightly larger thanthe inner diameter of the seal.

Referring now to FIGS. 2 and 3, the thrust washer seal 30 basicallycomprises an annulus having thrust-bearing surfaces 32 and 34 onopposite sides thereof. To seal grease on the side having the bearingsurface 32 against the adjacent inner thrust surface or face 36 of theyoke 12, the annulus has a circumferential flange 38 around itsoutermost edge which extends outwardly away from the surface 34. Flange38 extends outwardly from surface 34 a distance which is greater thanthe width of the annulus between the opposite bearing surfaces 32 and34, i.e., beyond surface 32, preferably by an actual amount which is onthe order of about one one-hundredth of an inch. This greater extensionof the flange insures contact between it and the yoke face 36, such thatwhen the seal is clamped between the center-block 14 and the yoke 12,the circumferential skirt-like edge 38 of the annulus is forced againstthe yoke surface 36, thereby flaring the skirt slightly and preventingleakage of grease past the skirt. The flange 38 of the annulus forms acircumferential groove 40 concentric with and inwardly adjacent theflange, and the thrust surface 32 defines circumferentially spaced andrecessed pockets 42 opening out into the groove 40. The groove 40 andthe pockets 42 thus define a walled area which encloses and retainsgrease, which is in continuous contact with the inner yoke surface 36.

The entire thrust washer seal 30 may be integrally molded of a plasticmaterial, which process readily lends itself to the manufacture of suchan article, particularly when the pockets 42 are spaced so that they areequally angularly positioned around the annulus. The preferred plasticis that which is sold commercially under the trademark Nylatron GS,"which comprises nylon with a molydisulfide impregnated therein. In thisform, the thrust washer has inherent Iubricous surface characteristics,which are definitely advantageous, as well as desired strength andthermal expansion characteristics.

To center and to seat the annulus 30 with respect to the center-block14, a relatively rigid annular flange 50 (FIG. 3) extends laterally fromthe surface 34 in a direction opposite to that of the aforementionedskirt or flange 38, flange 50 being located at the innermost diameter ofthe annulus and extending outwardly coaxially thereof. The flange 50 isof triangular cross section, and seats within an annular groove 52 (FIG.4) of complementary cross section formed around each of the trunnion pinopenings 19 in the center-block 14. As illustrated, the inner diameterof the annulus 30, and of its positioning flange 50, is larger than thediameter of the trunnion pins 18; consequently, the trunnion pins are atall times spaced from the thrust washer seal, since the groove 52 holdsthe latter in spaced coaxial relation by engaging the flange 50. Becausethe illustrated joint quite evidently requires four trunnion pins 18 topin the center-block 14 to the yokes 12, the center-block is formed withthe holes 54 and the annular grooves 52 on all of the four facesinvolved.

The basic structural parts of the joint can be formed from materialsconventionally used in joints of this general type; for example, theyoke may be a steel forging and the center-block formed from cold-rolledsteel, with the trunnion pins being roller bearing steel.

OPERATION It should now be apparent that by means of the thrust washerseal 30, thrust developed between the thrust surfaces 60 of center-blockl4 and the mating surfaces 36 of the yokes I2 is absorbed on the twobearing surfaces 32 and 34 of the seal, rather than being applieddirectly to these metal parts themselves. Furthermore, the flanges ofthe seal serve to keep grease in contact with the inner surfaces 36 ofthe yokes and with the trunnion pins 18, since flange 38 prevents lossof grease outwardly along the yoke surfaces and flange 50, in additionto positioning the seal, also prevents loss of grease outwardly alongthe block surfaces, thus retaining a tubular layer or coating of greasearound the trunnion pins in the space between the latter and the insidediameter of the seal. This retention of the grease insures that thegrease initially placed in the needle bearings 20 and on the trunnionpins will be retained, so as to prevent such bearings from breakingdown. Thus, it is not necessary to regrease the joint or hearing at anytime, thereby eliminating the need for structure which would otherwisemake the joint bulky and require a greater swing radius.

MODIFICATIONS FIG. 5 illustrates an alternate embodiment of theinvention, wherein the bearing assembly 20 has been omitted, as ispermissible where a considerably reduced load is carried by the joint.In this embodiment, parts which are similar to those illustrated in theprevious embodiment are labeled by the same numeral, with adistinguishing suffix a added thereto. Thus, joint a utilizes yokes 12apinned to a center-block 14a, but instead of fitting into a bearing, thetrunnion pin 18a is journaled directly in the yoke 12. Accordingly, thediameter of the hole drilled in the yoke 12a is reduced because of thenarrower diameter of the trunnion pin. As-in the previous embodiment, athrust washer seal 30a is utilized between the center-block and theyoke, and such element is constructed exactly as in the case of theprevious embodiment. Of course, since there is no bearing utilized inthis embodiment, the annulus comprising the seal is held in place onlyby the grooves in the center-block and by the closely adjacent surfacesof the yoke and center-block. The sealing action of this embodiment isin general the same as in the previous embodiment, however, and theadvantages of this feature in the present embodiment are quitesignificant, since not only is compactness a characteristic quality ofthe joint, but also the joint is sealed and permanently lubricated. I

Although the invention has been disclosed in connection with a universaljoint, it will be apparent that it can be applied to any joint utilizingmetal or like parts which are greased to reduce frictional engagementand which joint is desired to be permanently lubricated so that it neverhas to be disassembled during the life of the parts so joined. Asteering linkage is another example of a joint which could utilize theinvention.

It is entirely conceivable that upon examining the foregoing disclosure,those skilled in the art may devise embodiments of the concept involvedwhich difier somewhat from the embodiment shown and described herein, ormay make various changes in structural details to the presentembodiment. Consequently, all such changed embodiments or variations instructure which utilize the concepts of the invention and clearlyincorporate the spirit thereof are to be considered as within the scopeof the claims appended herebelow, unless these claims by their languagespecifically state otherwise.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.

1. In a universal joint, the combination of a center-block, a

yoke, pin means connecting said yoke to said block, and a thrust sealpositioned between a bearing surface of said block and said yoke, saidseal including at least one compressionbearing wall section ofpredetermined thickness between said block and said yoke, said wallsection defining a thrust-bearing surface and also defining pocketlikerecess means for sealing grease to prevent leakage thereof away fromsaid surface.

2. The combination as defined in claim 1, wherein said seal is anannulus having at least portions which are flexible.

3. The combination as defined in claim 1, wherein said sealing meansincludes a flange extending outwardly of said thrust surface at least aslight distance.

4. The combination as defined in claim 3, wherein said thrust seal is anannulus and said flange comprises an annular ridgelike formation.

5. The combination as defined in claim 4, wherein said flange is atleast slightly flexible.

6. The combination as defined in claim 1, wherein said thrust seal is anannulus, and further including a bearing means having an outer diameterslightly larger than the inner diameter of said annulus, said bearingbeing forcibly fitted within said annulus, and said bearing being of aninternal size such as to rotatably accommodate one end of said pin.

7. The combination as defined in claim 1, further including a generallycylindrical bearing means and an opening formed in said yoke forreceiving such bearing means, said bearing means having an outerdiameter of such size with respect to said opening as to be press-fittedtherein.

8. The combination as defined in claim 1, wherein said thrust seal hasat least one ridge means on the side thereof facing said bearingsurface, and wherein such surface of said block defines a recess forreceiving said ridge means therein to seat the thrust seal with respectto the block.

9. The combination as defined in claim 8, wherein said thrust seal is anannulus and is telescoped over said pin means, and wherein said ridgemeans includes portions which are generally oppositely disposed on saidannulus, such that the ridge means centers the annulus about said pinmeans.

10. The combination as defined in claim 9, wherein said pin means has anouter diameter which is larger than the inside diameter of said annulus,to define a space therebetween.

1. In a universal joint, the combination of a center-block, a yoke, pinmeans connecting said yoke to said block, and a thrust seal positionedbetween a bearing surface of said block and said yoke, said sealincluding at least one compression-bearing wall section of predeterminedthickness between said block and said yoke, said wall section defining athrust-bearing surface and also defining pocketlike recess means forsealing grease to prevent leakage thereof away from said surface.
 2. Thecombination as defined in claim 1, wherein said seal is an annulushaving at least portions which are flexible.
 3. The combination asdefined in claim 1, wherein said sealing means includes a flangeextending outwardly of said thrust surface at least a slight distance.4. The combination as defined in claim 3, wherein said thrust seal is anannulus and said flange comprises an annular ridgelike formation.
 5. Thecombination as defined in claim 4, wherein said flange is at leastslightly flexible.
 6. The combination as defined in claim 1, whereinsaid thrust seal is an annulus, and further including a bearing meanshaving an outer diameter slightly larger than the inner diameter of saidannulus, said bearing being forcibly fitted within said annulus, andsaid bearing being of an internal size such as to rotatably accommodateone end of said pin.
 7. The combination as defined in claim 1, furtherincluding a generally cylindrical bearing means and an opening formed insaid yoke for receiving such bearing means, said bearing means having anouter diameter of such size with respect to said opening as to bepress-fitted therein.
 8. The combination as defined in claim 1, whereinsaid thrust seal has at least one ridge means on the side thereof facingsaid bearing surface, and wherein such surface of said block defines arecess for receiving said ridge means therein to seat the thrust sealwith respect to the block.
 9. The combination as defined in claim 8,wherein said thrust seal is an annulus and is telescoped over said pinmeans, and wherein said ridge means includes portions which aregenerally oppositely disposed on said annulus, such that the ridge meanscenters the annulus about said pin means.
 10. The combination as definedin claim 9, wherein said pin means has an outer diameter which is largerthan the inside diameter of said annulus, to define a spacetherebetween.